Method and apparatus for making finned tubing



E. BRUEGGER Nov. 4, 1947.

METHOD AND APPARATUS FOR MAKING FINNED TUBING Filed April 17. 1945 3 Sheets-Sheet 1 EH a m n 05 E T U N Na R E 0 V5 m7 on. 5 M I H m 7/ Nov. 4, 1947. E. BRUEGGER METHOD AND APPARATUS FOR MAKING FINNED TUBING Filed April 17, 1945 s snets-sneet 2 INVENTOR I I C'/?IVJ7' BIN/f Ste BY I M ,M 7' 4 Il -X ATTORNEYS E. BRUEGGER Nov. 4, 1947.

METHOD AND APPARATUS FOR MAKING FINNED TUBING Filed April 17, 1945 3 Sheets-Sheet 3 Rm 2 N 0 R 8 f M E 0/: ATTORNEYS Patented Nov. 4, 19.41

METHOD AN D" APPARATUS. FOR MAKING Ernestv Bruegger, Massillon', l omt, as'signor-tc 'lhe GriscormRussell" Company, New York, Y., a." corporation ot Delaware- Application: April: 1 7; 1945, Serial Nor 588,800

' 1 :j" I This invention relates; to finned tubing-, and more particularly concerns" aniimprovecl method formakln'g finned: tubes of non-circular section and an improved apparatus" by means of which themethod may beperf'ormed;

Many forms of apparatusltor. transferring heat between, fluids or "other; materials ei'nploy' as their essential heat transfer element's tubes carrying.

fins on their outer: surfaces. Inflonewell' known construction, the flnlcomprisesja flat metallic; strip. or ribbon extending edgewise around the tube: and helically. along-its length witlrth'einner edge of the-striplon'ithetube-surface The helical fin may comprisean element-separate from the tube which iswound -edsew-ise about; the: tube and suitably-- secured thereto along the ,inner edge 1 of the. strip; a or the fin may be formed integral with: the tube;

In-some cases, itv is desirable tolprovide a, flnned tube of non-circular section.v l'lnparticular, a

finned tube of elliptical, oval or ,flattened. section. presents. certain advantages. With such a-tube",

fiuld'fiowing transversely. thereof-remains inhea't exchanging contact therewith'ind. with the fin;

structure thereon for "longer periods than with: circular section tubes, andmgilarger number of tubes 011 a given. cross sectionh Jen-ea. may bedisposed side by'side-across arduct or container: ore

givensize. I l I I It is: the object cit-the presentinvention1.02pm

vide an improved method' for tricking finned" tubesof non-circular and preferably elliptical, oval or fiattenedsection. Mor speciflcallyglthe invention contemplates a method by means of: which a, circular section helieally finnedtubepi the type described is shapedto-an elliptical, flattened" or otherwise transversely;elongated or noncircular section.

7 Another object of the invention is. to; provide: immcvecl apparatus by means ot gwhichahelicallv finned tube. or non-circular and preferably" elliptical'or fiattened'sectionmav be produced; More particularly, the inventiongcontemplates apps:

ratusfor: progressively shaping or. bending acircular section hellcally finned. tube to elliptical-or other non-circularcross sectional form, without 1a- Claims (61 153 ried outby employing: a. finned; tube of; circular section having; ahelicalifin: of the flat ed'gewis'e protruding; strip or ribbon ty pe 0n th'e tub' sur f ace, and? progressively compressing the tube an'd the. fin: transversely of the tube axis along; perti'ons 015- the fin and tube that: progress circumirentially of th'e structure 3 m: ahelical atmthe amount of suchzcompression'abein g; varie'd ini' timed relation tel the: progress-'-there'ofcircumterentially of the tube. The amount? of 'transvers'ecomprs si'o'n may: bezvariedibetween maximum and mini mum limitsiasthecompression-progressesthrough:

each successive: quarter: of the circumference-'01 the tube in order to, produce" a finned tube or elliptical on flattened 1' sectibrii The: pref erably: supported?- against? bending" orwarping movement lengthwise 01 the? tube during the progressive compresslorrof: thetube and thefiin Theapparatusofthe:inventicn includes meansfor supporting; a helically finned tube 1 while ad,- vancing-i it 1 relative to; one or more I pairs of compressing rollers' on equivalent means that simultaneously engage-the tube and at: dia'metri call? opposite: points, an'd that progress: clrcum' 'ferentially" of the: tube and -h'elicallyk along; its

length, together: witlr means. for successivelymoving the roller -sot? each? pair toward andi away from each: other-sin timedlrelation to: the -'relative movement of? the rollersi around. the-tube The rollers are preferably: tapered: to: progressively compress the tubeand" its: relativelysmall increments, and are also rpretera'bly' slotted so. as": t0 simultaneously: engace' the tube: surface thei fin edge; and to uppert the nh egainst move meritlengthwise:ctthetubetv In describing: the invention i'n detail; reference: will be made to the" acobmpa'nying; drawings in" which a typical embodiment ofviapparatus: involvlng;the inventicn andilcaliableoffcarryingcutathe V improvedi method: has been; illustrated? In the:

, drawings; v

Fig. 1" isapartial front' elevation of apparatus embodvinszthe invention;

loosening, warping or otherwise adversely: ail'ecting the fin orits attachment to the, tube.

Other objects ofthe invention include the pro-- vvision of a method and" apparatus capable of rapidly and economicallyshapingrcir'cular-sectionhelically finned, tubes to flattened, elliptical-= or other non-circular section without injuryto the:v

tube or the fin structure.

In general, the methods ofithe invention is car- E'ig, 2" is a seetionalzelevatlon 1 of the tube; shaning apparatus oni-anenlargediscel e;

Fig; 3 is an en'd elevationcii the tube and 'fin= compressing apparatus: taken along; the line s-3 of Fi 2 and viewed in" thedirection of the ar- IOWS;

Fig. 4-is'anendelevationof theappar'atus'show ing the tube supporting, mechanism and taken: along the line: 4 -4 offFig: z-and viewed in the direction: ofth'e' arrows; 1

= Fig; 5' is an enlarged view, partly'm section, showingv one of thepairsof tube andifin. com- V. 3 v pressingrollers at their positions oi. maximum transverse compression;

V Fig. 6 is an enlarged view similar to Fig. showing the pair of rollers at their position of minimum transverse compression; I

Figs. 7 and Sate respectively cross sectional views or finned tubes before and after being shaped to elliptical or flattened section in accordance with my improved method;

Fig. 9 is a longitudinal section of a tube carrying an integral helical tin; and

Fig. 10 is a longitudinal section of a tube carrying a helical fin formed separately from the tube. v I

Referring to the drawings and particularly 'to i5 Figs. 1 and2, the illustrated embodiment of my improved apparatus includes. a fixed tubular sup- 1 port H of appropriate length carried by suitable columns secured to a base It. The tubular support II is preferably somewhat longer than the longest finned tube to be shaped by the apparatus. A keyway l4 extends longitudinally throughout the bore otthe support 'l I, and a key l5 fixed to an'e l ns'lon bushing Ii which may besecured toa tube l'l rides freely-in the keyway l4. v

- The tube ll is theflnned tube which is to-be "shaped from circular to elliptical or flattened sec-, tion. In the illustrated embodiment, this tube icarries a helical fin "ion its outer surface, the

din being in the form of a thincontinuous strip or 'ribbon extending radially outward from the tube surface and circumferentially of the tube in a .helical path of equally spaced turns. The fin may beiormed integrally with the tube; and such a ysconstructionhasbeen illustrated in- Eig. 9 where 'the'tubellfcarries an integral helical fin i=8, A

more. usual-construction is illustrated in Fig. 10

tachrnent of the iin to the tube may be employed. -;;The tubular-supp rt. ll terminates in a circu- '.--;lar ;;.:flange -I9 ,i and a rotary head is journaled "om-the support ll adjacent its flanged end. As shown-,. the head 20 iscylindlrical and turns on anti-friction bearings 2| disposed between it and the support H An end plate 22 encloses the rearwardend of the bearing space, and a sealing ,ring 23 may be provi ded at the inner edge of the .end plate 22 for engagementjwith the. outer surfaceof the support I I. V A driving gear 24 is suitably fixed to the head 20 andis driven by a pinion 25 secured to a. drive shaft 26 carried in journals including the journal 21 fixed to thelbase I3. The shaft maybe driven by any suitable 'means sujchlasna motor,not shown, A bed 28 of a lengthat least as greatas that of the longest tube to be treated'is fixed toithe base {3 beyond the'end of the rotaryjhead 20.. A carriage 29 is slidably mounted on the bed 28 and the shaft 26 has a threadedportion 30 engaging a lug 3| .on

the carriage 29. With this arrangement, rotation of the shaft moves thecarriage 29 outward from of the tube ll is fixed to the sliding carriage 29 by any suitable means such as the expansion bushing 63. v 1 V .The outer end of the rotary headv 20 carries a plurality of'pairs of radially movable compressing rollers 32, 33 and 34, 35. .The rollers are of identical construction, and the rollers of each pair are arranged to move in diametrically opposite direc- 4 V tions radially of the head. As shown in Figs. 5 and 6, each of these rollers comprises a plurality of circular fin-like ridges 36 separated by valleys 31, and the rollers are tapered so that the diameters of the successive ridges 3S and valleys 31 increase outwardly from the head 20. The ridges as-nave a thickness substantially equal to the ably supporting the rollers 32, 33, 34 and 35 on the end of the head 20. In the disclosed embodiment. each of these rollers is journalld by means of a shaft 38 in a bifurcated bracket 39 secured by the bolts 40'to the inner face plate 4| of a sliding carriage 42. The carriage 42 includes a plate 43 which is slidably supported between overhanging track bars fixed toan outer face plate 45 iace of the pilot bushing and the inner end of each carriage plate43. With this arrangement, eachof the carriages 42 isbiased to move radially outwardirom the axis of rotation of the head 20. A cam follower roller 48 is rotatably journaled between arms 49 .at the outer end of each bracket 42.

A stationary internal cam surrounds the roller carrying brackets 42 and is engaged by the cam follower rollers 48. The cam '35 is suitably secured to a circular cam housing 66 carried by a support 81 secured to the base 13. As shown in Fig. 3, the inner edge of the cam 65 is elliptical, having its long axis substantially horizontal and itsshort axis substantially vertical. With this arrangement, as the head .20 rotates, the compression rollers of the pairs 3233 and 34-35, are movedbetween extremeclosely spaced and widely separated positions during each quarter of afrevolution of the head 20.

These extreme positions of the pair of rollers 32, 33am respectively illustrated in Figs. 5 and 6.

The openings in the face plate 4| of each carriage 42 through which the bolts 40 pass are considerably larger than the bolts so that the angle between the axis of rotation of the roller 32 and'the axis of the tube i! may be adjusted. By such adjustment, the compression rollers can be set to have the same load as the'helically wound fin 18 on the tube ll, whereby the ridges 36 of the compression rollers lie parallel to and between successive turns of the fin- 18 as the rollers are carried around the tube I! by the rotary head 20. The lead of the threads on the threaded portion 30 of the shaft '26 is so related i the head 20 along the bed 28in timed relation to' the rate of rotation of the head. The outer end to the ratio between the pinion-25 and the head gear 24 that the sliding carriage 29 is advanced by a. distance'equalto the spacing of successive turns of the helical -fin l8 during each "complete revolution of the head 20.

* axis:

above and below the tubes, as shown in Figs. 1. 2 and 4. As best shown in Fig. 4, the faces of these rollers 50 are concave so that together they form an-elliptical opening through which the -fiattened finned tube l1 passes. The rollers 50 are carried in journals ii and 52 which are "vertically slidable in frames 53 and 54 mounted of my apparatus in carrying out my improved method, a finned tube such as the tube il carrying the helical fin I8 is inserted in the bore of the support ii and the expansion bushing I8 is secured to the trailing end of the tube. The key I! on the bushing I6 is inserted in the keyway ll, the leading end of the tube being inserted through the pilot bushing 46. A length of the tube l1 adjacent its leading end preferably carries no fin turns, and this bare leading end is inserted between the compression rollers 32, 33, and 35, is compressed to elliptical shape byrotation of the head and is passed between the supporting rollers 60 and secured by the expansion bushing 63 to the carriage 29. The helical fin ill on the tube i1 is threaded into the valleys 31 of the compression rollers 32, 33, uqand 35. Rotation or the head 20 is continued, and the carriage 29 advances, drawing the tube 11 through the head 20. The advancing tube i1 is held against rotation by the engagement of the key IS in the keyway l4 and by the action of the supporting rollers 50. During the progress of the tube, the diametrically opposite'pairs of compression rollers 32, 33, 34 and 35 travel circumferentially around the tube I1 and simultaneously compress it and its fin taper of the compression rollers. The compression isapplied transversely of the tube by the pairs of compression rollers and this compression varie circumferentially of the tube between a maximum compression when each pair of oppositely disposed rollers lies in'a vertical plane through the tube axis and a minimum compression when each such pair or oppositely disposed rollers lies in a horizontal plane through the tube from circular to elliptical section in progressive stages as the tube advances. During this shaping, the fin is supported against buckling, bending oroth'er movement longitudinally of the tube by the ridges 36 on the compression rollers which l8 in progressive stages due to the path which comprises simultaneously compressing the tube and the fin transversely of the tube axis along portions thereof that progress circumferentially of the tube and in'the helical path of the fin along the tube length while supporting the fin against movement lengthwise of the tube, and varying the amount of such compression in timed relation to-the progress of the compression circumferentially of the tube.

2. The method of shaping to elliptical section a circular section tube having a flat fin extending edgewise from its surface along a helical path which comprises simultaneously compressing the tube and the fin transversely of the tube axis along portions thereof that progress circumferentially of the tube and in the helical path of the fin along the tube length, and varying the amount of such compression between maximum and minimum limits as the compression progresses through each successive quarter of the circumference of the tube. I

3. The method of shaping to elliptical section a circular section tube having a fiat fin extending edgewise from its surface along a helical path whichv comprises simultaneously compressing the tube and the fin transversely of the tube axis along portions thereof that progress circumferentially of the tube and inthe helical path of the fin along the tube length while supportin the fin The tube i1 and its fin i8 are thus shaped hold the fin therebetween. Since the compressive force is exerted simultaneously and equally on the tube surface and the fin edge, there i no tendency for the tube to separate from the fin during the shaping operation.

In the disclosed embodiment, the cam which governs the compressive movement of the compression rollers is elliptical in form with the result that the non-circular section towhich the finned tube is shaped is elliptical. The invention is not limited to this form of cam or finished tube, and it will beapparent that other noncircular sections of finned tube can be obtained by employing suitably shaped cams.

I claim:

1. The method of shaping to non-circular section a circular section tube having a flat fin ex tending edgewise from its surface along a helical against.,movement lengthwise of the tube, and successively increasing the amount ofsuch-compression to a maximum limit and decreasing such amount to a minimum limit as the compression advances through each successive quarter of the circumference of the tube. A H g 4. Apparatus for shaping to non-circular sec- .tiona circular section finned tube having a helical fin extending outwardly from its surface comprising spaced compression means for simultaneously engaging the tube fin and the tubeat diametrically opposite points, means for moving Said compression means circumferentially relative to the tube and helically, along the tube fin and means for moving said compression means toward and away, from each otheret ovapply. successively increasing and decreasing compression to the tube and the fin during such circumferential movement of said compression means,

5. Apparatus for shaping to non-circular section a circular section finned tube having a hellcal fin extending outwardly from its surface com prising a pair of spaced compression rollers for simultaneously engaging the tube fin and the tube surface at diametrically opposite points, means for moving said compression rollers circumferentially relative to the tube and helically along the tube fin and means for moving said compression rollers toward and away from each other to apply successively increasing and decreasing during such circumferential movement of said v compression rollers.

6. Apparatus for shaping to non-circular section a circular section finned tube having a helical fin extending outwardly from its surface comprising at least one pair of spaced circumferentially slotted compression rollersmeans for moving said rollers circumferentially around and relative to a finned tube with the'rollers disposed at diametrically opposite points relative to the tube axis and the fin of the tube passing through the slots of the-rollers, means for advancingthe finned tube longitudinally in timed relation to the circumferential movement of said rollers, and means for successively moving said rollers toward and advancing a tube Y I aperture between said rollers means for pre-' venting rotation of a tube so; ,advanced andvstathere'through, means the axis of said aperture, at

away-rromeach other as saidrollersimove cirtube longitudinall in timed relation to the cir-1 cumferentialmovement of-saidrollers, andgmeans operated in timed relation to the circumferential movement of saidrollers for moving said rollers .the vaxis of said-aperture. at spacedcompression rollers mounted on said head 'rr sinaa rotary headlhaving anlaxial aperture therethrough; means i or rotating saidxhead about least ;one pair of on opposite sides of its axis of rotation and movable radially of'such axis, means for advancinga helicallyfinn'edtube longitudinally through said headaper-ture between said rollers in timed A relation with there/2.01 rotation of said head,

toward and away from each vothera's said-rollers move circumferentially ofthetube-path;

8. Apparatus for shaping to non-circular sec- 1 -tion a circular section .finned tube having a helical fin extending outwardly from its Y surface comprising at least one pair-of ,spaced circumferentialiy' slotted-compression rollers, means for nroving said rollers circumterentiallyaround and relative to la flnnedtl be with the rollersdisposed at diametrically opposite -points relative to the tube axis and the finor'thetubepassing through the slots of the rollers, means 'foradvancing each other in timed relation said head, andmeanson said rollers for simulmeans for preventing rotation of .a tube so ad- -.vanced, meansfor successively moving said rollers radially ofsaid head toward and away from to the rotation of taneously compressively engaging the surface of a helical finned'tube and the edge of a fin thereon and for supporting the fin against movement longitudinally of the tube.

theflnned tube 1Ol8itudinally =in timed relation to the circumferential movement of said-rollers,

a cam extending-; 'circumferentlally around the path of the tribeadlacent saidrollers and having diametrically opposite high and low points,- means engaging saidkcarrijor moving said rollers toward and away ircrneach-cther as said rollers move}circumierentially of the tube Path.

9.- Apparatus helical fin extending outwardly-from its surface comprising a rotary head having "an axial aper-. ture therethrough, means-4oz rotating said head about the axis of saidaperture; at least one vp i o sre omm-na t ll r me i n said head on opposite'sidesof its axis of rotation and movable radially of"'such axis; .meansffor l ngitudinally of said head tionary means adiacentsaid head for successive- H 1y moving said rollers radially or said head toward and away from each other as said'head rotates. 10. Apparatus for I I tion a circular section finned tube having'a helical fln" extending outwardly irom' its surface cpmprising a rotary head having an axial aperture for rotating said head about spacedcompressicn rollers mounted on-sal'd head on opposite sides of its axis of rotationandmovable radially of such axis, means'io'r advancing a helically finned tube longitudinally through said head aperture between saidrollers in timed relation with the IQtG Of I'QtQ t'iOH of said'head,

means for preventingrotation of atube so'advancedymeans for successively moving said rollers radially of "said head toward and away from to: than; to Inonscircular sec-; 'tion a circularsection unnedtube "having a leastone pair of i ferential ridges and valleys on said rollers for respectively simultaneously compressively engagtionacircular; section v ,fin extending outwardly from its surface com- .on opposite sides movable radiallycf vancing a'helically firmedtube longitudinally .ofthe tube. in

12, Apparatus iorshapmg to nonkoircular sec- !inned tubehaving a helical prising a, rotary. head having an axial aperture therethrougmmeans for rotating said headabout theaxis of said aperture, at least one pair of rollers mounted onsaid head oi its axis of rotation and such axis, means for adspaced compression through said 7 head aperture between said rollers in .tirnedrelation with the rate of ,rotationoi said head, means for preventin'g'rotatibn voi :a

tube so advanced; means or successively moving said -,rollers-radially of said head toward and away Irom each other in timed relation to the rotation of said head, and a plurality of circuming thesuriaceoi a helically finned tube and the edge of the fin thereon, said ridges actingto supportthe fin against movement longitudinally 13. Apparatus for shaping to non-circularysectlon a circular section finned tube having a helical flnextending-outwardly from its surface comthe axis of said aperture, at

prising a rotary head having anax al aperture .therethrough, means ior rotating said head about least one pair. of

spaced compressionrollers mounted onsaid head .on opposite sides of itsraxis of rotation andmovable radially of such axis, means for, advancing a;helica-lly finned tube longitudinally through shaping to ncn-circularseca v;

each other in'timed relation tothe'rotation of said head, and means -On 's3 id rollers for simultaneously c'ompressively engaging the surface of a helical'finned tube and the vedge of'a helical finthereon; '1 7 '11; Apparatus for shaping to nontion a circular section finned tube having a helical fin extending outwardly from its surface comircular sec-' 7 said head aperture between said rollers in, timed relation with therate of rotation of said head, means for preventing rotation of a tube so advanced, means for successively moving said rollers, radially offsaid head toward and away from each other in timed relation to the ,rotationof .said head; and a plurality-oi circumferential ridgesand valleys: on said rollers of diameters that increase in the direction of the movement v.of said tube advancing means, said ridgesand valleys acting respectively to compressivelyengage the surface of a helically iinnedtube and the, edge of the fin thereon. a

. v ERNEST BRUEGGER.

Resonances or'r'nn Theiollowlng references are of recordlin the file of this patent:

v UNITED STATES PATENTS Number V H lName Date 1,661,908 Palmer Mar. 6, 1928 2,347,175 Dewey Apr. 25, 1944 2,385,498 Clifford Sept. 25, 1945 

